in the white house, a visibly shaken president obama offered these words about the mass killing. >> the majority of those who died today were children. beautiful little kids between the ages of 5 and 10 years old. they had their entire lives ahead of them. birthdays, graduations, weddings, kids of their own. among the fallen were also teachers. men and women who devoted their lives to helping our children fulfill their dreams. >> highly emotional president obama reflecting how most of the nation would have been feeling and tonight police have identified the killer as adam lanza. this is his brother ryan lanza being taken into questioning. much more on the shooter ahead. i'll talk to his former classmate. susan candiotti has new details from outside the school. a desperate day for the school and the families of the poor children and for america. what do we know about the person who perpetrated the hideous crime? >> reporter: you know, it is so heartbreaking, piers. we are learning he is 20-year-old adam lanza. we know according to our sources that for whatever reason when he came to the